bug: Gator launch skill recommends sandbox names rejected by the gateway #4659

User Story

I use OpenShell to run Gator against my own PRs. Launching it for #4633 with the contributor skill's suggested name failed.

Problem Statement

The launch skill recommends gator-pr-4633-supervised and validates names up to 63 characters, but the gateway limits sandbox names to 19. The launcher discovers this only after building the image and configuring providers.

Impact / Why This Matters

Following the documented workflow fails after expensive setup. Using gtr-pr-4633-watch worked.

Acceptance Criteria

• Skill examples and validation respect the 19-character limit.
• The launcher rejects invalid explicit or generated names before image builds or gateway changes.

Reproduction Steps

1. Follow launch-openshell-gator for PR docs(helm): document cert-manager operator mTLS setup #4633 on a healthy local gateway.
2. Pass --name gator-pr-4633-supervised to scripts/agents/run.sh --agent gator.
3. Observe image/provider setup followed by name exceeds maximum length (24 > 19).

Environment

• OpenShell gateway and installed CLI: 0.1.4
• OS: macOS ARM64
• Compute driver: local Podman

Suggested UX

Use --name gtr-pr-4633-watch; reject an oversized name immediately with a message explaining the 19-character DNS-label constraint.